1. Field of the Invention
The present invention relates to an improved joint for securely connecting a pair of telescopic tubes.
2. Description of Related Art
Conventional telescopic tubes normally comprise an outer tube, an inner tube slidably received in the outer tube and joint between them to connect the inner tube and the outer tube. As shown in FIGS. 8 and 9, a compression joint between an inner tube (3) and an outer tube (4) comprises a rubber inner tube plug (5), a rubber outer tube plug (6), a stop sleeve (8) and a bolt (7) with an enlarged head (71). The inner tube plug (5) defines an offset axial threaded hole (52) and a flange (51) formed on the bottom. The diameter of the inner tube plug (5) is the same as the inside diameter of the inner tube (3), and the diameter of the flange (51) is the same as the outside diameter of the inner tube (3) so that the inner tube plug (5) is stopped by the open end of the inner tube (3). The outer tube plug (6) defines an offset axial through hole (61) corresponding to the offset screw hole (52) of the inner tube plug (5). The bolt (7) is inserted through the through hole (61) of the outer tube plug (6) and into the screw hole (52) of the inner tube plug (5), so that the outer tube plug (6) is held in place by the head (71) of the bolt (7). The stop sleeve (8) is slid onto the inner tube (3), and the inner tube plug (5) and outer tube plug (6) combination is inserted into the inner tube (3). Then the inner tube (3) with the inner tube plug (5) and outer tube plug (6) is inserted into the outer tube (4), and finally the stop sleeve (8) is fit into the open end of the outer tube (4) to prevent the inner tube (3) from falling out by the friction of the combination of the inner tube plug (5) and the outer tube plug (6) with the stop sleeve (8). When a user turns the tubes in opposite directions, the outer tube plug (6) will press against the inner wall of the outer tube (4) to securely attach the inner tube (3) to the outer tube (4). When the tubes are turned in the opposite direction, the outer tube plug (6) is released from the inner wall of the outer tube (4) and the inner tube (3) is free to slide in the outer tube (4).
However, disadvantages of the joint include:
1 the life of the outer tube plug (6) is short, as the rubber material ages quickly, becomes brittle and wears excessively after a period of time, and PA0 2 the joint can only be used in circular tubes.